Field of the Invention
The present invention relates to wireless communication, and more particularly, to a method and device for a control channel decoding in a multi-node system.
Related Art
Recently, the amount of transmission of data of a wireless communication network is on a rapid increase. This is because various devices such as a smart phone and a tablet PC which require machine-to-machine (M2M) communication and a large amount of data transmission appear and are distributed. In order to satisfy the high amount of transmission of data, a carrier aggregation technology which efficiently uses more frequency bands, a cognitive radio technology, etc., are drawing attention, and in order to increase the data capacity within limited frequencies, a multi-antenna technology, a multi base station cooperation technology, etc. are drawing attention.
Furthermore, the wireless communication network is evolving in a direction that the density of nodes, which may have an access to the area around the user, increases. Here, a node may refer to an antenna or antenna group which is placed away by more than a certain interval from a distributed antenna system (DAS), but the meaning of the node may be extended. That is, the node may be a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a remote radio unit (RRU), a relay, etc. The wireless communication system may show a higher system performance by cooperation between nodes. That is, if each node operates like an antenna or antenna group for one cell by transmission and reception management by one control station, a much superior system performance may be shown. Hereinafter, a wireless communication including a plurality of nodes is called a multi-node system.
A node may be applied even if defined not only as an antenna group which is placed away by more than a certain interval, but also as an arbitrary antenna group regardless of an interval. For example, the base station composed of a Gloss polarized antenna may be formed of a node composed of a H-pol antenna and a node composed of a V-pol antenna.
Furthermore, in a multi-node system, a new control channel may be used due to inter-cell interference and an insufficient capacity in the existing control channel, etc. In the existing control channel, decoding was possible based on a cell-specific reference signal (CRS) which may be received by all user equipments (UEs), but in a new control channel, decoding may be possible based on a user equipment-specific reference signal (URS). The new control channel may be allocated to the data region among the control region and the data region in the subframe. In the 3rd generation partnership project (3GPP) long term evolution (LTE)/LTE-A(advanced), the existing control channel is called a physical downlink control channel (PDCCH) and a new control channel is called an enhanced-PDCCH (E-PDCCH).
In the existing control channel, control channel element (CCE) units have been used allocation, but in a new control channel such as E-PDCCH, the resource allocation unit may be the resource block (RB). That is, a greater resource allocation unit maybe used.
In this case, a new control channel may transmit a control signal through more wireless resources compared to the existing control channel, and thus a greater coding gain may be obtained, and an additional beam gain may be obtained through beam forming.
Considering the above, if a control signal is transmitted in a new control channel using a modulation scheme as in the existing control channel, the operation may be performed at an unnecessarily high signal to interference plus noise ratio (SINR). Hence, the modulation scheme in a new control channel introduced in the multi-node system is an issue, and from the perspective of the UE, the modulation/decoding scheme of a new control channel is an issue.